Process for production of synthetic crude oil from low temperature coal tars

ABSTRACT

A PROCESS FOR THE PRODUCTION OF SYNTHETIC CRUDE OIL FROM LOW TEMPERATURE COAL TARS WHICH HAVE BEEN OBTAINED BY CAREFUL TEMPERATURE CONTROL DURING THE CARBONIZATION OF VARIOUS COOL MATERIALS, SUCH AS COAL.

United States Patent Ollice 3,576,734 Patented Apr. 27, 1971 3,576,734PROCESS FOR PRODUCTION OF SYNTHETIC CRUDE OIL FROM LOW TEMPERATURE COALTARS Harold L. Bennett, Indianapolis, Ind., assignor to BennettEngineering Company, Rnshville, Ind. No Drawing. Filed Sept. 25, 1968,Ser. No. 762,611 Int. Cl. C10g N US. Cl. 208-8 Claims ABSTRACT OF THEDISCLOSURE A process for the production of synthetic crude oil from lowtemperature coal tars which have been obtained by careful temperaturecontrol during the carbonization of various cool materials, such ascoal.

SUMMARY OF THE INVENTION This invention relates to an improved processfor the economical production of synthetic crude oil. The syntheticcrude oil is obtained from low temperature coal tars which have beenobtained by carefully controlling the temperature during thecarbonization of various cool materials such as coal.

Generally speaking the synthetic crude oil and accompanying gaseousproducts are obtained by introducing heated low temperature tars withhydrogen into an insulated drum containing a suitable catalystcomprising one or more of the following elements: cobalt, molybdenum ornickel. The residence time of the combined heated low temperature tarsand hydrogen in the presence of the catalyst is sufiicient to produce apetroleum-like synthetic crude oil. A batch or continuous type processmay be used to accomplish the formation of an expanded high-type"synthetic crude oil. This expanded high grade synthetic crude oil fromwhich most of the fixed or organic sulphur has been removed during theprocess contains a large percentage of naphtha and is ready for furtherprocessing. Following removal of the naphtha fractions by methods wellknown in the art, the bottoms product or remainder of the syntheticcrude can be introduced as a recycle into the low temperature tarsentering the system.

The synthetic crude oil formed by the process of the present inventioncan be refined by any of the processes well known in the petroleumindustry. End products after refining, deepnding on the variation ofheat, pressure and time that the low temperature tars and hydrogen arein contact with the catalyst will contain high percentages of aromatichydrocarbons, amines, phenols, parafiins, olefins and various otherlight end materials. Gaseous products formed will contain hydrogen,light end gases, nitrogen compounds, and hydrogen sulfide, all of whichcan be processed into marketable products.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the practice of the presentinvention carbonaceous material, such as bituminous coal and the like,is introduced into a suitable roaster, such as multi-hearth verticalroaster, under controlled temperature with the gases removed at eachlevel to avoid overheating. The solid material is retained in theroaster from two to four hours at a temperature of from between 400 to600 centigrade. The rotation speed of the roaster arms and the feed isregulated to assure the desired retention time. The roaster armspreferably move the material along with a plowtype action. The roasterpreferably has a heat exchange and induction center at the bottomthereof for the introduction of the super heated steam. The exhaustresulting This exhaust is treated to separate the hydrogen and carbonmaterials and the hydrogen is retained for subsequent use.

After the hot gases have been removed the remaining soild material, highvolatile char, are removed mechanically from the roaster, cooled, andmarketed or further processed into producer gas which in turn ismarketed for heating or refined into light end products.

The hot distillation gases emitted at the various levels of the roasterare cleaned and condensed into low temperature tars with the remaininggases sent to the light end plant. At this point approximately 1200 to1500 cubic feet of hydrogen is added to each barrel of low temperaturetar and salvaged bottoms and the mixture is brought into contact with afixed bed catalyst under controlled pressure, heat and time. A singleautoclave-type batch unit having a void to catalyst ratio of from 1:1 to4:1 can be advantageously used, or a continuous flow through unit with aliquid hourly space velocity (oil-to-catalyst volume ratio) of from 1.5to 4.0 can be used. The pressure in the units is maintained from between700 to 2000 p.s.i., and the temperature is maintained between 350 to 500C. Generally, the tars are passed through a primary reactor at atemperature between 350-370 C., and are then passed through a secondreactor at a temperature of from 450 to 490 C. The resulting effiuent isthen cooled into synthetic crude oil and gases. After cooling, the gasescon taining hydrogen sulfide, hydrogen, various light end hydrocarbonsand nitrogen compounds are removed and further processed.

The hydrogen gas can be recycled and introduced into the low temperaturetar stream entering the reaction chamber or burned as a flare gas. Thehydrogen sulphides can be processed to produce a commercial sulphur orprocessed with hydrogen to produce commercial acids. The lighthydrocarbons can further be refined in light end units where yieldedoff-gases are erturned for production heat. The nitrogen compounds canbe converted into commercial fertilizer, acids and other products.

The low temperature tar which has been converted into a synthetic crudestock is then processed in a conventional petroleum distillation unit toyield a naphtha product boiling below 250 C. and a series of gases whichare utilized in light ends plant or burned as excess. The syntheticcrude after removal of the naphtha and light end gases becomes residualand can be recycled with low temperature tars or further treated to formvarious grades of asphaltic material, fuel oils and lubricating stock.

The material removed from the distillation unit as a naphtha out can befurther procesed into regular petroleum products or petrochemicalsutilizing any number of refining processes known to the art. The lightends plant consist of polymerization, alkylation and/or isomerizationunits. The phenols can also be processed into commercial units.

The invention claimed is:

1. A process for preparing an esentially sulfur free synthetic crude oilwhich comprises the steps of:

(a) Roasting bituminous coal at a temperature of about 400 to 600 C. forabout '2 to 4 hours,

(b) Continuously collecting and condensing the distillation gases,

(c) Separating the low temperature tars from the condensed gaseousproducts.

(d) Contacting the low temperature tars with a cobaltmolybdenum catalystin a fixed bed system heated to a temperature of 350 to 500 C. and apressure of 700 to 200 p.s.i. in the presence of hydrogen added in anamount equal to 1200 to 1500 cubic feet of hydrogen per barrel of lowtemperature tars,

(e) Cooling the efliuent from the reactor and separating the gaseousproducts containing hydrogen, hydrogen sulfide and nitrogen compoundstherefrom and (f) Recovering the essentially sulfur free synthetic crudeoil product.

2. A process according to claim 1 wherein the low temperature tars arefed into a primary reactor maintained at a temperature of 350 to 370 C.and then passed thru a second reactor heated to a temperature of 450 to490 C.

3. The process according to claim 1 wherein the low temperature tars arecontacted in an autoclave unit with a void space to catalyst ratio of1:1 to 4: 1.

4. The process according to claim 1 wherein the low temperature tars arecontacted in a continuous flow thru unit at a weight hourly spacevelocity of 1.5 to 4.0.

5. The process according to claim 1 wherein the bituminous coal isroasted at about 400 to 600 C. in the presence of steam.

References Cited UNITED STATES PATENTS 1,879,750 9/1932 Joseph 208-8 101,702,899 2/1929 Howard 208-8 1,954,096 4/1934 Pier 2088 DELBERT E.GANTZ, Primary Examiner 15 V. OKEEFE, Assistant Examiner

